Stoker furnace



March 30,`1937.

Filed May l6,` 1935 f H. E. PRESTON STOKER FURNACE 2 shears-sheet 1 March 30,V 17937. H. E. PRESTON Y sToKER FURNACE Filed May 16, Y1955 2 Sheets-Sheet 2.

Patented Mar. 30, 1937 UNITED STATES PATENT OFFICE STOKER FURNACE Pa., a corporation of Application May 16,

'7 Claims.

This invention relates to stoker furnaces, and more particularly to the fuel feeding mechanisms associated with such devices.

In stoker furnaces it is necessary to change the rate of fuel feed in accordance with the load conditions under which the furnace is operating. When mechanical operating mechanisms are employed to operate the fuel feeding elements, variable speed gear constructions may be employed to change the rate of fuel feed. The present invention, however, relates to the type of stokers employing fluid pressure means for operating the fuel feeding elements and in such cases variable speed gears or other mechanical constructions cannot be employed. In underfeed stokers of this type there is usually provided one main ram and one or more auxiliary rams or pushers for each fuel retort, and fluid pressure is introduced to reciprocate the main rams while mechanical means connect the auxiliary rams or pushers to the main ram for simultaneous movement therewith.

The present invention has for its primary object the provision in stokers of the stated character, means for varying the quantity of fuel fed per cycle of movement of each ram.

A more specific object is to provide in stokers wherein the rams are operated by fluid pressure, adjustable stop means which is adapted to halt the ram at different predetermined positions before they reach their limit of travel in the return direction and thereby change at will the quantity of fuel fed per cycle of movement of each of the rams.

Other and further objects will become apparent as the description of the invention progresses.

Of the drawings:

Fig. 1 is a longitudinal section view taken through the forward portion of one of the retorts of an underfeed stoker of the multiple retort type, showing the operating means for the rams and pushers thereof.

Fig. 2 is an end view partly in section taken substantially along line 2--2 of Fig. l.

Fig. 3 is an end view partly in section showing the stop mechanism for the ram in one position of adjustment.

Fig. 4 is a similar view showing the stop mechanism in a second position of adjustment.

Fig. 5 is a similar view showing the stop mechanism in a third position of adjustment, and

Fig. 6 is a perspective view of the stop mechanism and its adjusting means.

Referring to the drawings, the numeral I des- 55 ignates the front wall of a furnace, equipped with Pennsylvania 1935, Serial No. 21,819

a Stoker 2 of the general type embodied in my pending application Ser. No. 542,383, filed June 5, 1931, and assigned to the American Engineering Company. A ram 3 operates in a cylinder 4, secured against the outer face of the wall I. inder 4 has provided at the top thereof a port 5 which communicates with the bottom of a fuel hopper 6. The ram 3 when in an advanced position closes the port 5 and when said ram is retracted fuel from hopper 6 gravitates into cylinder 2, which fuel is projected by the ram in its next advance movement through a port 'I in the front wall I onto a dead plate 8 which constitutes the upper bottom portion of one of a series of retorts 9 which, with the intermediate tuyres I0, constitutes the fuel supporting section of the Stoker whereon combustion of the fuel occurs.

Each of the retorts is provided with a series of reciprocatory pushers II Vwhich constitute with the alternately disposed dead plates I2 the bot-- tom walls of the retorts. Reciprocation of pushers I I effects a progressive movement of the fuel over the fuel suporting section of the Stoker in a Well known manner. As shown in Fig. 1, the ram 3 which, as will be apparent from the above description, constitutes one of a series of rams associated individually with the respective retorts of the stoker, is hollow, and is open at its front end for reception of a stationary piston I3.

The front end of the hollow ram is closed byA means of a head I4 which has an opening for the passage therethrough of a rod I5 to the rear'- end of which the said piston I3 is secured. In the present instance the piston I3 is provided with an internally threaded bore to which is secured'the correspondingly threaded inner end of the rod I5. The joint between the head I4 and the cylinder 4 is sealed by means of a suitable gasket, and suitable packing is provided between the rod I5 and the head I4 to prevent leakage from the interior of the ram. The rod I5 is rigidly 'secured at its outer end to a bracket I6,

secured at its upper end directly to the cylinder 4 and at its forward and lower end to an extension bracket I1, attached to the lower-forward end of cylinder housing 4. The rod I5, as illustrated in the drawings, is provided with spaced longitudinal passages I8 and I9 respectively, which communicate at the outer end of therod with a pair of pipes 20 and 2I, which in turn are respectively connected to a pair of main pipes 22 and 23. Pipes 22 and 23 are connected to any suitable pumping apparatus (not shown). The inner end of passage I8 is closed in the present instance by means of a plug 24 threaded into in- Cylner end of rod I3. Passage I8 is provided with one or more ports 25 which communicate with an annular recess 26 provided at the outer end of piston I3. The ports 25 are provided for application of fluid pressure between piston I3 and head I4 of the ram 3. The inner end of passage I9 communicates directly with the chamber at the inner end of piston I3 and provides for application of fluid pressure between the piston l0 and the inner end of the hollow ram. Preferably, the hollow ram 3, the passages I8 and I 9, pipes 2U and 2|, and main pipes 22 and 23 form with the pumping apparatus (not shown) a closed fluid circuit, and in operation the associated pump operates to evacuate the ram chamber at one side of the piston I3 and to apply fluid pressure to the other side whereby the hollow ram is caused to reciprocate within the cylinder 4 in the performance of the fuel feeding function above described. The pumping apparatus for performing this function may be of a reversible discharge type which functions alternately through a pressure control mechanism (not shown) associated therewith to apply fluid pressure and to evacuate the interior of the ram 3 at opposite sides of the piston to effect the aforesaid reciprocatory movement of the ram. One form of reversing control mechanism for effecting a reverse operation of the ram 3 is shown in United States Patent No. 1,895,627, granted January 31, 1933, and assigned to the American Engineering Company. In such constructions when the ram reaches the limit of its travel in either direction a pressure builds up at the pressure side thereof which is communicated to the reversing apparatus. When this pressure reaches a predetermined value the discharge of the pump is reversed causing the side of the piston formerly subjected to pressure to now be connected to the suction side of the pump and the side of the piston formerly connected to exhaust to be connected to the pressure side of the pump, and as a result the ram is operated in the reverse direction. When the ram again reaches its limit of travel in the new direction pressure again builds up and a reverse yoperation of the ram is again effected in the manner just described.

Inasmuch as the specific type of reversing mechanism above described forms no part of the present invention, a detailed description thereof is unnecessary. The present invention, however, as will be hereinafter more fully described, deals with a mechanism designated generally at 28, which functions to interrupt the movement of the ram 3 during its return movement and to causesuch pressures to be built up therein as to effect a reverse operation thereof and thus vary the quantity of fuel fed by the ram at each cycle of movement thereof.

The bracket I1 forms a journal for a rock shaft 30 to the opposite ends of which are secured levers 3|. 'I'he upper ends of these levers are secured through the medium of links 32 to the opposite sides of the ram head I4, while between the lower ends of said levers is pivotally mounted in the present instance a block 33 which is apertured for the reception of one or more rods 34. Rods 34 are connected through a suitable coupling 35 to rods 36 which extend through bearing brackets 31, secured to the lower portion of the front Wall I of the furnace. Rods 36 are operatively connected to the pushers I I through any suitable link and lever mechanism indicated generally at 39. Means is also provided, as illustrated in Fig. 1, for adjusting rods 34 with respect to the common operating levers 3I. Each of rods 34 has secured thereto a collar 46 adapted to abut the inner side of block 33 and the outer end of each of said rods has secured thereto a terminal collad 4I. Intermediate the collars 40 and 4I the rods are adapted for reception of one or more horseshoe washers 42, the number and position of which determines the operative relation between the rods 34 and the block 33. It will be noted that the primary ram 3 constitutes in itself the main actuating member for the auxiliary rams or pushers II, and that by interposing the lever 3| between the ram 3 and the operating rods 34 a highly flexible connection is established affording a desired adjustment between the individual fuel feeding pushers.

The mechanism 28 for varying the quantity of fuel fed by the main rams 3, at each cycle of movement thereof, will now be described in detail.

As shown more particularly in Figs. 1 and 6, this mechanism is mounted on the inner surface of the front wall 45 of bracket I6 and comprises a pair of spaced segmental discs 46 and 41 which are connected for simultaneous movement by a connecting link 48. Disc 46 is secured to the inner end of a shaft 49 journaled in a suitable bearing 50 provided in the lower portion of wall 45. The outer end of shaft 49 has secured thereto a hand lever 5I which is adapted to adjust discs 46 and 41 to different positions of adjustment. Disc 41 is pivotally mounted on a pintle 52 extending through an aperture provided near the upper end of wall 45, and a pair of lock nuts 53 and 54 prevent lateral movement of disc 41. Disc 46 has secured to the inner surface thereof inwardly extending projections 55, 56 and 51 of different lengths and which are mounted about the arcuate upper end 58 of said disc.

around the substantially arcuate portion 62 thereof and which projections correspond in length with projections 55, 56 and 51 respectively of disc 46. Discs 46 and 41 are somounted on' the front wall 45 of bracket I6 that the projections thereon are adapted to engage the outer face of head I4 when the ram 3 is moved outwardly or in the return direction of its movement. When the parts are in the position shown in Fig. 3, the shortest projections 51 and 6I of discs 46 and 41 respectively lie in the path of movement of head I4, while the longer projections mounted on these discs are so disposed as not to interfere with the movement of said ram. When the parts are in the position shown in Fig. 4 the intermediate projection 56 of disc 46 and the corresponding projection 60 of disc 41 will lie in the path of head I4 and thereby prevent movement of the ram beyond this point. Again, when the parts are in the position shown in Fig. 5 the longest projections 55 and 59 of discs 46 and 41 respectively, lie in the path of movement of head I4 and thereby still further shorten the return stroke of said ram. As pointed out before, when the movement of ram 3 is interrupted in this manner the pressure causing the movement of the ram builds up, and through the reversing mechanism previously described, a reverse operation thereof will be effected.

Referring to Fig. 1, it will be noted that when the movement of ram 3 is interrupted by the intermediate and the longest projections 56, 60 and 55, 59, as above described, a portion of the rear end thereof covers a portion of port 5 between cylinder 4 and hopper 6. As a result a Disc 41 has also secured thereto inwardly extending projections 59, 60 and 6I, extending smaller quantity of fuel will gravitate into the end of cylinder 4 than would enter the same if the ram had moved to fully retracted position. The extent to which the port 5 is covered in this manner is determined by the length of these projections. By this means it is seen that the quantity of fuel fed by each of the rams per cycle of movement thereof may be varied.

In the present instance the stroke control mechanism is provided with three adjustments although it is obvious that any number of such adjustments may be employed as desired. Lever 5l has provided thereon intermediate its ends a spring urged detent 65 which is adapted to engage in apertures BS provided at the front face of bracket I1 so as to effectively lock lever 5l in its different positions of adjustment.

It therefore is seen that a simple but highly effective means is provided for regulating the fuel fed to a stoker furnace employing hydraulic means for actuating the fuel feeding elements thereof.

It is believed to be quite apparent that other means may be provided for limiting the movement of the ram and thereby eecting a change in the quantity of the fuel fed per cycle of movement thereof, and accordingly, it is to be understood that the invention is not to be limited to the single embodiment herein shown, but only by the scope of the claims which follow.

What is claimed is:

l. In a device of the class described, the combination of a feeding ram, fluid pressure means for actuating said ram, adjustable stop means for interrupting the movement of said ram during its travel in the return direction, said stop means comprising a pivotally mounted disc having a series of inwardly extending projections of different lengths mounted thereon, and means for actuating said disc to bring the desired one of said projections into the path of said ram.

2. In a device of the class described, the combination of a feeding ram, fluid pressure means for actuating said ram, adjustable stop means for interrupting the movement of said ram during the return travel thereof, said stop means comprising a pair of interconnected discs pivotally mounted in spaced relation, each of said discs having secured thereto a series of inwardly extending projections of different lengths, and means for actuating said discs to bring the corresponding of said projections thereon into the path of said ram to interrupt the movement of the latter during its travel in the return direction.

3. In a device of the class described, the combination of a ram cylinder, a fuel feeding ram operating in said cylinder, a fuel hopper mounted on said cylinder having a port at the bottom thereof through which fuel may gravitate into said cylinder when said ram m-oves toward retracted position, fluid pressiue means for reciprocating said ram, and abutment means adapted to engage said ram to interrupt the movement thereof during its travel in the return direction, whereby said port is partially covered thereby and a correspon-dingly smaller quantity of fuel is fed by said ram at the next feeding stro-ke thereof.

4. In a device of the class described, the combination of a ram cylinder, a fuel feeding ram operating in said cylinder, a fuel hopper mounted on said cylinder having a port at the bottom thereof through which fuel may gravitate into said cylinder when said ram moves toward retracted position, fluid pressure means for reciprocating said ram, and adjustable abutment means adapted to engage said ram to interrupt the movement thereof at different predetermined positions lduring its travel in the return direction whereby said port is partially covered thereby and correspondingly smaller quantities of fuel are fed by said ram at the next feeding stroke thereof.

5. In a device of the class described, the combination of a ram cylinder, a fuel feeding ram operating in said cylinder, a fuel hopper mounted on said cylinder having a port at the bottom thereof through which fuel may gravitate into said cylinder when sai-d ram moves toward retracted position, fluid pressure means for reciprocating said ram, means for regulating the quantity of fuel gravitating into said cylinder, said means comprising adjustable abutment means adapted to engage said ram to interrupt the movement thereof -during its travel in the return direction whereby said port is partially covered and a correspondingly smaller quantity of fuel is fed by said ram upon the next feeding stroke thereof.

6. In a device of the class described, the combination of a ram cylinder, a fuel feeding ram operating in said cylinder, a fuel hopper mounted on said cylinder having a port at the bottom thereof through which fuel may gravitate into said cylinder when said ram moves toward retracted position, fluid pressure means for reciprocating said ram, means for regulating the quantity of fuel gravitating into said cylinder, said last mentioned means comprising a pivotally mounted disc having a series of inwardly extending projections of different lengths mounted thereon, an-d means for actuating said discs to bring the desired one of said projections into the path of said ram, thereby interrupting the movement of said ram at different predetermined positions during its travel in the return direction whereby said p-ort is partially covered by said ram an-d correspondingly smaller quantities of fuel are fed by said ram at the next feeding stroke thereof.

7. In a device of the class described, the combination of a ram cylinder, a fuel feeding ram operating in said cylinder, a fuel hopper mounted on said cylinder having a port at the bottom thereof through which fuel may gravitate into said cylinder when said ram moves toward retracted position, fluid pressure means for reciprocating said ram, means for regulating the quantity of fuel gravitating into said cylinder, said last mentioned means comprising a pair of interconnected discs mounted in spaced relation, each of said discs having secured thereto a series of inwardly extending projections of different lengths, and means for actuating Said discs to bring the corresponding of said projections thereon into the path of said ram, thereby interrupting the movement of said ram at different predetermined positions during its travel in the return ldirection whereby said port is partially covered by said ram and correspondingly smaller quantities of fuel are fed by said ram at the next fee-ding stroke thereof. A

HERBERT E. PRESTON. 

